In this paper, Matrimid® 5218 glassy polymer, which is predominantly used for fabrication of the dense gas separation membranes, was applied to fabricate porous ultrafiltration (UF) membranes for liquid phase filtration. The prepared bare and mixed matrix membranes (MMMs), containing different weight percentages of graphene oxide (GO) nanoplates were characterized by SEM, ATR-FTIR, and AFM analyses along with water contact angle (WCA), average pore radius, and porosity measurements. The SEM images displayed an asymmetric structure where the incorporation of hydrophilic GO nanoplates has resulted in construction of more and larger finger-like macrovoids in the sublayer. The optimum membrane, containing 0.02 wt% of GO nanoplates offered the overall porosity of 86.9%, average pore radius of 5.48 nm, as well as the highest pure water flux (PWF) and flux recovery ratio (FRR%) of 266 L m